1. Field of the Invention
The present invention relates generally to a mobile communications system and, more particularly, to a device and method for determining initial transmission power for a forward link channel on which a base station transmits a signal to a mobile station in a mobile communications system.
2. Description of the Related Art
Referring to FIG. 1, there is a diagram illustrating a situation where the initial transmission power for a new forward link channel must be determined. A base station (BS) transmits a reference pilot channel and other channels to a mobile station (MS), and the mobile station transmits an access channel, a reverse pilot channel and other channels to the base station. In order that the base station transmits a new channel to the mobile station, it is necessary for the base station to determine the initial transmission power for the forward link channel. The term xe2x80x9cthe other channelsxe2x80x9d as used herein refers to traffic channels and control channels and the term xe2x80x9ctraffic channelsxe2x80x9d refers to channels for transmitting data and voice information.
In the conventional related art mobile communications system, the base station sets the initial transmission power for the forward link channel to a fixed value irrespective of the channel condition. Here, there are some cases where the base station uses a higher transmission power than is needed, because surplus power is required to allow the mobile stations to receive specified information in all situations. Therefore, the related art power control method has the effect of increasing forward link interference, especially, interference between adjacent cells by not determining transmission power according to the channel condition. This results in deterioration of the receiving performance at the mobile stations and inefficient utility of power at the base station. Accordingly, the related art power control method is problematic in that the base station for the mobile communications system cannot determine the initial transmission power to an optimum value at a point of time it starts to transmit traffic channels or control channels to a specified mobile station.
It is, therefore, an object of the present invention to provide a device and method for determining initial transmission power for a forward link channel in a mobile communications system.
It is another object of the present invention to provide a device and method for determining initial transmission power for a forward link channel in a mobile communications system, in which a mobile station measures the strength of a specified channel signal transmitted by the base station and a base station determines the initial transmission power for a forward link channel signal according to the measured value received from the mobile station.
It is further another object of the present invention to provide a device and method for determining initial transmission power for a forward link channel in a mobile communications system, in which a base station measures the strength of a specified channel signal transmitted by the mobile station and determines the initial transmission power for a forward link channel signal.
It is still further another object of the present invention to provide a device and method for determining initial transmission power for a forward link channel according to a data rate in a mobile communications system.
It is still further another object of the present invention to provide a device and method for determining initial transmission power for a forward link channel in a mobile communications system, in which a base station measures the strength of a reverse link pilot channel signal to determine the initial transmission power for the forward link channel at a point of time it starts to transmit traffic channels or control channels to the mobile station.
It is still further another object of the present invention to provide a device and method for determining initial transmission power for a forward link channel in a mobile communications system, in which a base station determines the initial transmission power for the forward link channel according to the strength of a pilot channel signal reported by a mobile station at a point of time it starts to transmit traffic channels or control channels to the mobile station.